Electrical brush plating system and method for metal parts

Abstract

An electrical brush plating system and method for metal parts wherein a motion control member and a plating bath with a plating pen includes an anode member provided with an anode plate and bristles that are mounted on the motion control member. A part to be plated is disposed within the plating bath with the bristles provided towards the surface of the part to be plated and under the control of the motion control member, the bristles perform a relative friction motion with the surface of the part to be plated. During the relative friction motion, the surface of the part to be plated is opposite to the anode plate of the anode member. The method includes the steps of mounting the plating pen and the part to be plated; electrocleaning; strong activation; weak activation and electrical brush plating. The generation of pinholes, pits and nodules are avoided.

The invention claimed is: 
     
       1. An electrical brush plating system for metal parts, comprising:
 a motion control means; 
 a plating bath; 
 a DC power supply; 
 a plating pen mounted on the motion control means, and containing a rotational anode member having a hollow cavity provided with an anode plate with associated bristles, the anode member being made of bakelite materials that are non-conductive; 
 a part to be plated positioned in the plating bath by a positioning apparatus provided in the plating bath; 
 said bristles extending toward the surface of the part to be plated and adapted to perform a frictional motion with the surface of the part to be plated by the motion control means; wherein 
 during the frictional motion, the surface of the part to be plated is positioned opposite to the anode plate of the anode member, wherein a certain section of the surface of the part to be plated does not perform a relative frictional motion with the bristles at all times during the entire electrical brush plating process; 
 the part to be plated is connected to the negative pole of the DC power supply; and 
 the anode plate is connected to the positive pole of the DC power supply; 
 the plating pen is adapted for external cylindrical parts, said plating pen comprising the anode member having a hollow cylindrical structure with a lower open end, an inner wall of the anode member being provided with the anode plate containing at least one set of the bristles having a long strip shape, the bristles being oriented towards the surface to be plated of the external cylindrical part disposed within the hollow cavity of the anode member, the bristles on the rotational anode member, being under the control of the motion control means for performing the frictional motion with the surface of the external cylindrical part to be plated, the surface to be plated being positioned opposite to the anode plate on the inner wall of the anode member, 
 wherein the distance between the surface of the part to be plated and the anode member is between 45 mm and 55 mm and a magnitude of interference of the contact between the bristles and the surface of the part to be plated, which performs a relative frictional motion with each other, is between 2 mm and 3mm. 
 
     
     
       2. The electrical brush plating system for metal parts as recited in  claim 1 , wherein the motion control means comprises a motor which controls the rotational motion of the plating pen, the motor containing an output shaft extending vertically downward and provided with a clamp, and a mounting rod provided on top of the plating pen is fixedly disposed in the clamp, so that the plating pen is in a suspended and fixed state. 
     
     
       3. The electrical brush plating system for metal parts as recited in  claim 1 , which further comprises a liquid supply and distribution means which includes a plurality of liquid supply tanks containing different solutions for electrical brush plating, the output ports of the respective liquid supply tanks are connected to a liquid infusion port of the plating bath through a peristaltic pump, a liquid discharge port of the plating bath being connected to a corresponding return port of the liquid supply tanks through the control of a dispense motor, wherein filter cartridges are installed at the return ports of the respective liquid supply tanks. 
     
     
       4. An electrical brush plating method for metal parts which implements the electrical brush plating system for metal parts as claimed in  claim 1 , the electrical brush plating method comprising the following steps:
 step 1: the plating pen and the part to be plated are installed; 
 step 2: electrocleaning: an electrocleaning solution is poured into the plating bath, the DC power supply and the motion control means are turned on, and the surface of the part to be plated performs a relative frictional motion with the bristles, in the electrocleaning process, the cathode current density is between 1 A/dm 2  and 100 A/dm 2 , when a set electrocleaning time is reached, the DC power supply and the motion control means are turned off, the electrocleaning solution is discharged, and then a rinse with clean water is performed for at least two times; 
 step 3: strong activation: a strong activation solution is poured into the plating bath, the DC power supply and the motion control means are turned on, and the surface of the part to be plated performs a relative frictional motion with the bristles, in the strong activation process, the cathode current density is between 1 A/dm 2  and 200 A/dm 2 , when a set strong activation time is reached, the DC power supply and the motion control means are turned off, the strong activation solution is discharged, and then a rinse with clean water is performed for at least two times; 
 step 4: weak activation: a weak activation solution is poured into the plating bath, the DC power supply and the motion control means are turned on, and the surface of the part to be plated performs a relative frictional motion with the bristles, in the weak activation process, the cathode current density is between 1 A/dm 2  and 100 A/dm 2 , when a set weak activation time is reached, the DC power supply and the motion control means are turn off, the weak activation solution is discharged, and then a rinse with clean water is performed for at least two times; 
 step 5: electrical brush plating: a plating solution is poured into the plating bath, the DC power supply and the motion control means are turned on, and the surface of the part to be plated performs a relative frictional motion with the bristles, in the electrical brush plating process, the speed of the relative motion of the bristles with respect to the surface of the part to be plated is controlled between 10 m/min and 20 m/min, the cathode current density is between 10 A/dm 2  and 25 A/dm 2 , when a set electrical brush plating time is reached, the DC power supply and the motion control means are turned off, the plating solution is discharged, and then a resin with clean water is performed for at least two times. 
 
     
     
       5. The electrical brush plating method for metal parts as claimed in  claim 4 , wherein:
 when the anode plate is a soluble nickel plate, the plating solution consists of nickel sulfate, boric acid, nickel chloride and water, wherein the contents of nickel sulfate, boric acid and nickel chloride are 260-300g/L, 41-50g/L and 60-80g/L, respectively. 
 
     
     
       6. The electrical brush plating system for metal parts as recited in  claim 2 , wherein the electrical brush plating system for metal parts comprises a liquid supply and distribution means which includes a plurality of liquid supply tanks containing different solutions for electrical brush plating, respectively, output ports of the respective liquid supply tanks are connected to a liquid infusion port of the plating bath through a peristaltic pump, a liquid discharge port of the plating bath is connected to a corresponding return port of the liquid supply tanks through the control of a dispense motor, filter cartridges are installed at the return ports of the respective liquid supply tanks. 
     
     
       7. An electrical brush plating system for the external plating of metal parts which comprises:
 a plating bath for housing a plating substance, 
 a positioning apparatus disposed in the plating bath for positioning a part to be plated within the plating bath, 
 a plating pen having a configuration which is adapted to surround the external surface of the part to be plated, said plating pen functioning as an anode member having a hollow cavity provided with an anode plate and facilitating a frictional effect by being provided with bristles which extend toward the surface of the part to be plated for frictional engagement therewith, the anode member being made of bakelite materials that are non-conductive, 
 a motion control means operatively connected to the plating pen to position and rotate the plating pen relative to the part to be plated, wherein the bristles of the plating pen are adapted to not perform a relative friction motion with the bristles all the time during the entire electrical brush plating process on a certain section of the surface of the part to be plated by the motion control means, and 
 a DC power supply having a positive pole connected to the anode member and a negative pole communicating with the part to be plated, 
 wherein the distance between the surface of the part to be plated and the anode plate is between 45 mm and 55 mm, and a magnitude of interference of the contact between the bristles and the surface of the part to be plated, which perform a relative frictional motion with each other, is between 2 mm and 3 mm. 
 
     
     
       8. The electrical brush plating system for the external plating of metal parts as claimed in  claim 7 , wherein the motion control means comprises a motor which controls the rotational motion of the plating pen, the motor being connected to a control system and provided with an output shaft disposed vertically downward, with a clamp provided thereon, and a mounting rod is connected to the top of the plating pen and is fixedly controlled by the clamp, so that the plating pen is positioned in a suspended state.